Chromospheric evolution and the flare activity of super-active region NOAA 6555

Super-active region NOAA 6555 was highly flare productive during the period March 21st–27th, 1991 of its disk passage. We have st udied its chromospheric activity using high spatial resolution Hα filtergrams taken at Udaipur along with MSFC vector magnetograms. A possible relationship of flare productivity and the variation in shear has been explored. Flares were generally seen in those subareas of the active region which possessed closed magnetic field configuration, whereas only minor flares and/or surges occurred in subareas showing open magnetic field configuration. Physical mechanisms responsible for the observed surges are also discussed.     

地幔对流与岩石层板块的相互耦合及影响──（Ⅱ）地幔混合对流理论及其应用

观测到的板块运动包含两种能量分布几乎相等的运动形态：极型场和环型场．纯粹的由热驱动的地幔自由对流不能预期和解释环型运动的产生．本文提出地幔混合对流理论,既考虑了热驱动的自由对流,也考虑了由板块自身激发的强迫对流．根据板块处于动力学平衡状态的观测事实,建立了相应的模型．数值结果表明,根据混合对流模型所预期的板块速度场,既能产生极型场,也能产生环型场,而且在空间分布特征及功率谱分布上与观测资料符合相当好．地幔物质的上升流动基本和洋脊对应,而下降流动和俯冲带对应．     

Has the crab pulsar magnetic field grown after its birth?

We investigate the evolution of rotation period and spindown age of a pulsar whose surface magnetic field undergoes a phase of growth. Application of these results to the Crab pulsar strongly indicates that its parameters cannot be accounted for by the field growth theories.     

基于DTW与K-means算法的河北场雨及雨型分区特征研究

深入挖掘气象站点的观测降雨数据,研究区域降雨的雨型规律,对于洪涝灾害预警和减灾措施制订有重要意义.本文基于河北省2005-2017年3189个站点逐小时降雨观测数据,进行"场雨"的划定,进而提取历史上各场雨的累积雨量、时长指标.采用数据挖掘技术中的DTW相似性算法进行场雨雨型的自动归类,将场雨分成Ⅰ-Ⅶ共7种雨型,包括...     

甘肃北山地区红山铁矿硅质岩的地球化学特征及沉积环境

通过野外地质调查和系统的岩石主量元素、微量元素、稀土元素等的研究,探讨红山铁矿床硅质岩的地球化学特征及其沉积环境。红山铁矿床中广泛发育一套与铁矿体呈共生关系的硅质岩。研究表明,与铁矿密切共生的呈层状和透镜状产出的灰色、紫红色硅质岩总体属于低硅类型的硅质岩。在SiO2-Al2O3判别图解中,SiO2与Al2O3负相关,样品数据点均落入热水沉积区域;稀土元素配分模式经北美页岩标准化后呈平缓型,与东太平洋热泉水、红海热卤水具有相似的正Eu异常和配分模式,δEu值均大于1,显示热水沉积的特征;硅质岩中的V、Ni、Cu、Ba等微量元素的含量具有陆缘海盆热水沉积的特征。     

桂西南晚泥盆世锰矿床锰质豆鲕粒类型及其成因探讨

桂西南锰矿赋存于上泥盆统五指山组中段,产锰矿三层,大多由锰质豆鲕粒组成。笔者研究了下雷锰矿床的锰质豆鲕粒,按其形态、结构构造和矿物成份划分为16种类型,并据①其沉积环境属断陷深水台沟相;②富集于几个矿段;③其碳酸锰矿物δC~(13)值为-6.23～-7.78‰,说明碳源于深部岩浆;④豆鲕粒由菱锰矿,蔷薇辉石、黑云母、锰铁叶蛇纹石、绿泥石、柘榴石等热液矿物组成。因此认为,锰质豆鲕粒形成于海底热气液喷溢口及其附近热水流动带,而低温滞水带不易形成豆鲕粒。     

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???ú??CORS?????????4???GPS????????????GAMIT/GLOBK??????е??????????????????????????????????????????????????????????????????????????3???????????????150 mm??11?′??????????4??????????????????10 mm/a????????溯?????????????????????????????????6′×6′?????????????????????????????????     

城市生态环境分区遥感综合分析--以贵阳市城区为例

建设环境良好的城市是人居环境应用研究的重点领域。而人居环境的研究则涉及到宏观和中、微观层次,是自然生态系统和人工生态系统的结合。在建设可持续发展的人居环境的过程中,遥感、地理信息系统、全球定位系统技术对空间数据和属性数据处理、管理、分析可以发挥积极的作用。本文以贵阳市城区为例,探讨了"3S"技术在人居环境研究中城市生态环境分析,以期对贵阳市城市规划提出具体的改进建议,使之更符合建设良好的人居环境的要求。     

Thin accretion disc with a corona in a central magnetic field

We study the steady-state structure of an accretion disc with a corona surrounding a central, rotating, magnetized star. We assume that the magneto-rotational instability is the dominant mechanism of angular momentum transport inside the disc and is responsible for producing magnetic tubes above the disc. In our model, a fraction of the dissipated energy inside the disc is transported to the corona via these magnetic tubes. This energy exchange from the disc to the corona which depends on the disc physical properties is modified because of the magnetic interaction between the stellar magnetic field and the accretion disc. According to our fully analytical solutions for such a system, the existence of a corona not only increases the surface density but reduces the temperature of the accretion disc. Also, the presence of a corona enhances the ratio of gas pressure to the total pressure. Our solutions show that when the strength of the magnetic field of the central neutron star is large or the star is rotating fast enough, profiles of the physical variables of the disc significantly modify due to the existence of a corona.